17alpha, 21-dihydroxypregnene esters as antiandrogenic agents

ABSTRACT

The present application provides 17 and/or 21 esters of 17α,21-Dihydroxypregna-4,9(11)-diene-3,20-dione and 17α,21-dihydroxypregna-4-ene-3,20-dione having remarkable antiandrogenic activity, methods of using these compounds, and processes for their preparation.

The present invention relates to 17α,21-dihydroxypregnene esters,processes for the preparation thereof and the use thereof asantiandrogenic agents.

PRIOR ART

A number of corticosteroids have been used as anti-inflammatory,anti-rheumatic, anti-allergic and anti-shock agents.

In particular, 11-deoxy-hydrocortisone esters and derivatives thereofhave been widely used as anti-inflammatories.

No 17α,21-dihydroxypregnene mixed esters are known, while 17 and 21 acylderivatives with equal aliphatic chains having no more than four carbonatoms have been described.

Carboxylic acids 17 or 21 monoesters having no more than six carbonatoms are also known.

U.S. Pat. No. 3,530,038 discloses a process for the preparation of11β-17α-21-trihydroxy steroids which comprises subjecting11-deoxy-17α-OR-21-OR′ steroids, wherein R is a carboxylic acid residueof 1-18 carbon atoms and R′ is hydrogen or an acyl of 1 to 18 carbonatoms, to microbiological oxidation with Curvularia for obtaining thecorresponding 11β-hydroxy steroid.

U.S. Pat. No. 3,780,177 discloses the preparation of21-hydroxy-pregna-4,9-diene-3,20-dione-17α-butanoate by means oforthobutyrates and the use thereof as an intermediate for thepreparation of 6α,9α-difluoroprednisolone 17-butanoate-21 esterderivatives.

SUMMARY OF THE INVENTION

It has now been found that some17α,21-dihydroxypregna-4,9(11)-diene-3,20-dione and17α,21-dihydroxypregna-4-ene-3,20-dione 17 and/or 21 esters haveremarkable anti androgenic activity.

Therefore, according to a first embodiment, the present inventionrelates to compounds of formula (I)

wherein:R₁ and R₂, which can be the same or different, are hydrogen or a C₃-C₁₈acyl group, with the provisos that:

at least one of R₁ and R₂ is different from hydrogen;

when R₁ is hydrogen, R₂ is different from butyroyl.

According to a second embodiment, the invention relates to compounds offormula (II)

wherein:R₁ and R₂, which can be the same or different, are hydrogen or a C₃-C₁₈acyl group, with the proviso that:

at least one of R₁ and R₂ is different from hydrogen;

as antiandrogenic drugs.

According to a further embodiment, the invention relates to a processfor the preparation of compounds of formula (I) or (II) in which R₁ andR₂ are both acyl groups, which process comprises reacting thecorresponding compounds, wherein R₁ and R₂ are hydrogen, with carboxylicacids anhydrides or active esters in inert solvents and at temperaturesranging from −5° C. to the reaction mixture boiling temperature.

Still a further object of the invention relates to a process for thepreparation of compounds of formula (I) or (II) wherein one of R₁ or R₂is hydrogen and the other is acyl, which process comprises:

-   a. reaction of the corresponding compounds wherein R₁ and R₂ are    hydrogen with C₃-C₁₈ carboxylic acids anhydrides or active esters or    with allyloxycarbonyl chloride or isobutene in inert solvents and at    temperatures ranging from −5° C. to the boiling temperature, for    obtaining the corresponding compound in which R₁ is isobutyl,    allyloxycarbonyl or C₃-C₁₈ acyl;-   b. optional reaction of the compound from step a) with C₃-C₁₈    carboxylic acids anhydrides or active esters in inert solvents and    at temperatures ranging from −5° C. to the reaction mixture boiling    temperature;-   c. optional lysis of the 21-allyloxycarbonyl or 21-isobutyloxy    group.

Finally, the invention relates to pharmaceutical compositions withantiandrogenic activity containing as active ingredient the compounds offormula (I) or (II).

DETAILED DISCLOSURE OF THE INVENTION

Preferred compounds of formula (I) are:

-   17α,21-dibutanoyloxy-pregna-4,9(11)-diene-3,20-dione;-   17α-hydroxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione;-   17α-butanoyloxy-21-octadecanoyloxy-pregna-4,9(11)-diene-3,20-dione;-   17α-octadecanoyloxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione.

The antiandrogenic activity of the compounds of formula (I) and (II) hasbeen evaluated in the animal according to the conventional test for thetopical antiandrogenic activity described by W. Voigt and S. L. Hsia(Endocrinology 1973; 92: 1216-1222).

The test was carried out on sexually immature female hamsters aged 6-8weeks and weighing 65-90 grams.

At the beginning of the tests, the back of each animal was shaved toevidence the respective flank organ bilaterally. Animals were thensubdivided into homogeneous groups and treated daily for 21 consecutivedays. The tested steroids were dissolved at concentrations ranging from100 to 400 micrograms in 50 microliters of an acetone solutioncontaining 4 micrograms of testosterone propionate (TP) or 4 microgramsof dihydrotestosterone (DHT). 50 Microliters of the solutions wereapplied to the right flank organ, while the contralateral organ used asindividual control received only acetone (50 microliters). Controlgroups received TP or DHT alone, following the same procedures.

At the end of the tests, the animals were killed under ether anesthesiaand the whole skin of the back was taken. The area of both flank organswas measured, separately, with transillumination. The mean differencesbetween areas treated with the tested steroids and those treated withthe carrier alone were calculated for each group, and said meandifferences were compared, as inhibition percentages, to the meandifferences between the areas in the control groups treated with eitherTP or DHT.

As shown in Examples 6 and 7, the compounds described herein inhibitedby more than 80% the androgenic action of testosterone propionate (TP)and by 50 to 80% the action of its active derivative dihydrotestosterone(DHT).

The compounds of the invention proved active at doses ranging from 10 to4000 micrograms.

The compounds of the invention can be used as suitable pharmaceuticalcompositions for the topical and/or systemic treatment, through theoral, cutaneous or mucosal route, of conditions such as: acne,seborrhea, hirsutism, alopecia, mastodynia, prostate hyperplasia andcarcinoma, virilization syndromes in the female, early puberty,inhibition of sexual aggressiveness in the male, contraception in themale.

According to the process of the invention, compounds of formula (I) or(II) wherein R₁ and R₂ are both acyl groups are prepared byesterification of 17α,21-dihydroxypregna-4-ene-3,20-dione or17α,21-dihydroxypregna-4,9(11)-diene-3,20-dione hydroxy groups withactive esters containing the desired acyl group. According to thissimple procedure, acyl derivatives with hindering aliphatic chains, suchas those with high number of carbon atoms or branched, can be prepared.Examples of suitable active esters for this reaction are trifluoroethylbutyrate or trifluoroethyl octadecanoate, which can both attainexcellent esterification yields with the aid of a lipase in inertanhydrous solvents at temperatures ranging from 20 to 50° C. and withreaction times ranging from 20 to 100 hours. Examples of lipases are PPL(porcine pancreatic lipase) or those from Candida cylindracea.

The process for the preparation of the compounds of formula (I) or (II)wherein one of R₁ or R₂ is hydrogen and the other is acyl comprises thefollowing steps:

1. The 21 hydroxyl is selectively esterified with allyloxycarbonylchloride, benzyloxy carbonyl chloride, tert-butylcarbonyl chloride indimethylformamide or isobutene at temperatures from −5 to 40° C.

2. The resulting 21 monoester is then subjected to esterification withanhydrides of carboxylic acids of 7 carbon atoms in the presence of4-dimethylaminopyridine as catalyst. Alternative to the esterificationin 17 is the use of the carboxylic acid in the presence ofdicyclohexylcarbodiimide. Active esters such as trifluoroethylderivatives or N-acylphthalimide or N-acylbenzotriazoles are furtheralternatives.

3. The protection in 21 is removed with, for example,tetrakis(triphenylphosphine) Pd and triphenyl phosphine indichloromethane or tetrahydrofuran to obtain17α-acyloxy-21-hydroxypregna-4-ene-3,20-dione or17α-acyloxy-21-hydroxypregna-4,9(11)-diene-3,20-dione.

4. The product from step 3) can subsequently be esterified in 21 withanhydrides of carboxylic acids of 7 carbon atoms or alternatively withthe carboxylic acid in the presence of dicyclohexylcarbodiimide, or withactive esters such as trifluoroethyl derivatives or N-acylphthalimidesor N-acylbenzotriazoles.

Example 1: Preparation of17α,21-dibutanoyloxy-pregna-4,9(11)-diene-3,20-dione

A mixture of 1 g (2.87 mM) of17α,21-dihydroxy-pregna-4,9(11)-diene-3,20-dione and of 10 ml oftrifluoroethyl butanoate in 50 ml of tetrahydrofuran was reacted at 45°C. in the presence of 5 g of Candida cylindracea lipase for 8-10 hours,adding 1 g of lipase at regular time intervals. At the end of this firstreaction step, the lipase was filtered off and the filtrate wasconcentrated under vacuum taking up the residue three times withtetrahydrofuran. The resulting residue was added with further 10 ml oftrifluoroethyl butanoate and 50 ml of tetrahydrofuran, the resultingsolution was added with 0.8 g of Bacillus subtilis protease and thesuspension was stirred for 2 days at 45° C., adding further protease atregular time intervals for total 80 mg. The protease was filtered off,the filtrate was removed under vacuum and the residue waschromatographed on a silica gel column with a dichloromethane/methanol99:1 mixture. The less polar fraction was evaporated to obtain 1 g (2.06mM) of 17α,21-dibutanoyloxy-pregna-4,9(11)-diene-3,20-dione.

The same procedure was followed, starting from 1 g of17α,21-dihydroxy-pregna-4-ene-3,20-dione, to obtain 0.98 g (2.01 mM) of17α,21-dibutanoyloxy-pregna-4-ene-3,20-dione.

Example 2: Preparation of17α-hydroxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione

A mixture of 1 g (2.879 mM) of17α,21-dihydroxy-pregna-4,9(11)-diene-3,20-dione and 10 ml oftrifluoroethyl butanoate in 100 ml of acetone was reacted at 45° C. inthe presence of 5 g of Candida cylindracea lipase for 8-10 hours, adding1 g of lipase at regular time intervals. After completion of thereaction, the lipase was filtered off and the filtrate was concentratedunder vacuum, taking up the residue three times with acetone. Thesemi-solid residue was purified by chromatography on a silica gel columnwith a dichloromethane/methanol 99:1 mixture. The less polar componentswere removed, to obtain the richer fraction which was evaporated toyield 0.95 g (2.29 mM) of17α-hydroxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione.

Example 3: Preparation of17α-hydroxy-21-butanoyloxy-pregna-4-ene-3,20-dione

A mixture of 1 g of 17α,21-dihydroxy-pregna-4-ene-3,20-dione and 10 mlof trifluoroethyl butanoate in 50 ml of methyl ethyl ketone was reactedat 45° C. in the presence of 5 g of Candida cylindracea lipase for 8-10hours, adding at regular time intervals 1 g of lipase. After completionof the reaction, the lipase was filtered off, the filtrate wasconcentrated under vacuum, taking up the residue three times withsolvent. The semi-solid residue was purified by chromatography on asilica gel column with a dichloromethane/methanol 99:1 mixture. Thericher fraction was evaporated to obtain 0.89 g (2.14 mM) of17α-hydroxy-21-butanoyloxy-pregna-4-ene-3,20-dione.

Example 4: Preparation of17α-butanoyloxy-21-octadecanoyloxy-pregna-4,9(11)-diene-3,20-dione

4 g (11.6 mM) of 17α,21-dihydroxy-pregna-4,9(11)-diene-3,20-dione werereacted with 20 mg of trifluoroacetic acid in 20 ml of dioxane and 10 mlof ethyl orthobutyrate for 5 hours at 100° C., and the low boiling headfraction was distilled off. The solution was cooled, then treated with 5ml of a tartaric acid molar solution and heated to 40-50° C. for about 5minutes to obtain17α-butanoyloxy-21-hydroxy-pregna-4,9(11)-diene-3,20-dione. The solventwas evaporated off under vacuum and the residue was repeatedly taken upwith dioxane. The resulting residue was dissolved in 200 ml of acetoneand then 12 g trifluoroethyl octadecanoate (prepared from octadecanoylchloride and trifluoroethanol), 20 g of Candida cylindracea lipase wereadded and the resulting suspension was stirred for 8-10 hours at 50° C.,adding 2 g of C. cylindracea at regular time intervals. The lipase wasfiltered off, the filtrate was concentrated under vacuum and the residuewas chromatographed on a silica gel column with adichloromethane/methanol 98.5:1.5 mixture. The neat fraction wasevaporated to obtain 4.9 g (7.17 mM) of17α-butanoyloxy-21-octadecanoyloxy-pregna-4,9(11)-diene-3,20-dione.

The same procedure was followed, starting from 5 g (14.5 mM) of17α,21-dihydroxy-pregna-4-ene-3,20-dione, to obtain 5.9 g (8.61 mM) of17α-butanoyloxy-21-octadecanoyloxy-pregna-4-ene-3,20-dione.

Example 5: Preparation of17α-octadecanoyloxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione

Step a:

A solution of 2 g of NaOH in 20 ml of water was added with 25 ml oftetrahydrofuran and 5 g (14.5 mM) of17α,21-dihydroxy-pregna-4,9(11)-diene-3,20-dione. The mixture wasstirred at 0° C., then 2.4 ml of allyl chloroformate was dropwise added.After stirring for about 0.5 hours at this temperature, the mixture wascarefully neutralized with hydrochloric acid and extracted withdichloromethane. The organic extract was concentrated under vacuum andthe residue was subjected to the reaction of the subsequent step.

Step b:

Crude 17α-hydroxy-21-allylcarbonyloxy-pregna-4,9(11)-diene-3,20-dionewas dissolved in 15 g of trifluoroethyl octadecanoate and 150 ml oftetrahydrofuran, the resulting solution was added with 4 g of Bacillussubtilis protease and the suspension was stirred for 2 days at 45° C.,adding further protease at regular time intervals to 3 g total. Theprotease was filtered off, the filtrate was removed under vacuum and theresidue was chromatographed on a silica gel column with adichloromethane/methanol 99:1 mixture. The less polar fraction wasevaporated off to obtain a residue of17α-octadecanoyloxy-21-allylcarbonyloxy-pregna-4,9(11)-diene-3,20-dione.

Step c:

the residue from the previous step was dissolved in 50 ml ofdichloromethane and added with 35 mg of triphenylphosphine and 35 mg ofpalladium triphenylphosphine. The resulting mixture was stirred for 0.5hours at room temperature. The solution was concentrated under vacuum,the residue was taken up twice with dichloromethane, thenchromatographed on a silica gel column with a dichloromethane/methanol99:1 mixture. The richer fraction was evaporated to obtain a neatresidue, which was used as such for the subsequent step.

Step d:

the residue (6.2 g) of17α-octadecanoyloxy-21-hydroxy-pregna-4,9(11)-diene-3,20-dione wasdissolved in 4 ml butyric anhydride in the presence of 0.5 g oftributylmethylammonium chloride. The mixture was stirred at roomtemperature for 2 hours, then poured in ice and the resulting productwas separated from water by extraction. The extract was washed toneutrality with water and concentrated under vacuum, the residue wascrystallized from methanol to obtain 5.5 g (8.05 mM) of17α-octadecanoyloxy-21-butanoyloxy-pregna-4,9(11)-diene-3,20-dione. Thiscompound was used for the preparation of a pharmaceutical formulation inthe form of a cream suitable for cutaneous administration.

The same procedure was followed, starting from 5 g (14.5 mM) of17α,21-dihydroxy-pregna-4-ene-3,20-dione, to obtain 5.1 g (7.44 mM) of17α-octadecanoyloxy-21-butanoyloxy-pregna-4-ene-3,20-dione.

The compounds of Examples 1-5 were formulated in suitable formulations,for example in the form of liposome emulsions or suspensions for thetransmucosal administration to provide either systemic or topicalaction, creams, gel and the like.

A typical cream formulation will contain, for example, cetyl alcohol,glycerol monostearate, liquid paraffin, propylene glycol, disodiummono-oleo-amide sulfosuccinate, citric acid monohydrate, purified water.

Using substantially the same methods disclosed in the above examples,the following compounds were prepared:

-   -   17α, 21-dibutanoyloxy-pregna-4-ene-3,20-dione (mp 101° C.,        isopropyl ether);    -   17α-propionyloxy-21-hydroxy-pregna-4-ene-3,20-dione (mp 114° C.,        isopropyl ether).

Example 6: Topical Antiandrogenic Activity (Compound of Example 1)

Topical Mean difference of treatment Daily dosage (μg) the areas (mm²) %inhibition Carrier (acetone) — 0.0 — TP 4 22.7 ± 2.3 — TP + Ex. 1 4 +400  3.7 ± 1.1 89 DHT 4 20.8 ± 2.5 — DHT + Ex. 1 4 + 400  3.7 ± 0.7 82

Example 7: Topical Antiandrogenic Activity (Compound of Example 2)

Topical Mean difference of treatment Daily dosage (μg) the areas (mm²) %inhibition Carrier (acetone) — 0.0 — TP 4 22.7 ± 2.3 — TP + Ex. 2 4 +400  3.3 ± 1.2 85 DHT 4 20.8 ± 2.5 — DHT + Ex. 2 4 + 400  4.1 ± 0.5 80

What is claimed is:
 1. A method of preparing a compound according toformula II:

wherein R₂ is a C₃-C₁₈ acyl group, the method comprising: selectivelyesterifying a compound of Formula III

to give a compound of Formula IV

wherein R₁ is an alcohol protecting group capable of being removed witha palladium catalyst; esterifying the compound of Formula IV to give acompound of Formula V

and; selectively deprotecting the compound of Formula V to give thecompound of Formula II.
 2. The method of claim 1, where R₂ is—C(O)CH₂CH₃.
 3. The method of claim 1, wherein R₁ is allyloxycarbonyl orbenzyloxycarbonyl.
 4. The method of claim 1, wherein selectivelyesterifying a compound of Formula III to give a compound of Formula IVcomprises reacting the compound of Formula III with allyloxycarbonylchloride, benzyloxycarbonyl chloride, or tert-butylcarbonyl chloride. 5.The method of claim 4, wherein the reacting takes place in a solvent atfrom −5° C. to 40° C.
 6. The method of claim 5, wherein the solvent isdimethylformamide or isobutene.
 7. The method of claim 1, whereinesterifying the compound of Formula IV to give a compound of Formula Vcomprises reacting the compound of Formula IV with a carboxylic acidanhydride in the presence of a catalyst.
 8. The method of claim 7,wherein the catalyst is 4-dimethylaminopyridine.
 9. The method of claim1, wherein esterifying the compound of Formula IV to give a compound ofFormula V comprises reacting the compound of Formula IV with acarboxylic acid in the presence of a carbodiimide.
 10. The method ofclaim 9, wherein the carbodiimide is dicyclohexylcarbodiimide.
 11. Themethod of claim 1, wherein esterifying the compound of Formula IV togive a compound of Formula V comprises reacting the compound of FormulaIV with an active ester.
 12. The method of claim 11, wherein the activeester is a trifluoroethyl active ester, an N-acylphthalimide activeester, or an N-acylbenzotriazole active ester.
 13. The method of claim1, wherein selectively deprotecting the compound of Formula V comprisesreacting the compound of Formula V with a palladium catalyst.
 14. Themethod of claim 13, wherein the palladium catalyst istetrakis(triphenylphosphine) palladium.
 15. The method of claim 13,reacting the compound of Formula V with a palladium catalyst takes placein dichloromethane or tetrahydrofuran.